The Fujimoto-Belleau reaction is a chemical reaction

Chemical reaction

A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Chemical reactions can be either spontaneous, requiring no input of energy, or non-spontaneous, typically following the input of some type of energy, such as heat, light or electricity...

 that forms cyclic α-substituted α,β-unsaturated ketone

Ketone

In organic chemistry, a ketone is an organic compound with the structure RCR', where R and R' can be a variety of atoms and groups of atoms. It features a carbonyl group bonded to two other carbon atoms. Many ketones are known and many are of great importance in industry and in biology...

s from enol

Enol

Enols are alkenes with a hydroxyl group affixed to one of the carbon atoms composing the double bond. Alkenes with a hydroxyl group on both sides of the double bond are called enediols. Deprotonated anions of enols are called enolates...

 lactone

Lactone

In chemistry, a lactone is a cyclic ester which can be seen as the condensation product of an alcohol group -OH and a carboxylic acid group -COOH in the same molecule...

s. The reaction is named after the two chemists George I. Fujimoto

George I. Fujimoto

George I. Fujimoto is an American chemist of Japanese descent. During his studies in Harvard his family was imprisoned in an American internment camp Minidoka in Idaho. He discovered the Fujimoto-Belleau reaction, which is named after him and Bernard Belleau....

 and Bernard Belleau

Bernard Belleau

Bernard Belleau, OC, FRSC was a Canadian molecular pharmacologist best known for his role in the discovery of Lamivudine, a drug used in the treatment of HIV and Hepatitis B infection....

.

The reaction is a Grignard reaction, followed by a H-shift, an enol-keto tautomerisation

Tautomer

Tautomers are isomers of organic compounds that readily interconvert by a chemical reaction called tautomerization. This reaction commonly results in the formal migration of a hydrogen atom or proton, accompanied by a switch of a single bond and adjacent double bond...

 and an Aldol addition reaction. The last step is an elimination (Aldol condensation) reaction with an E₁CB mechanism.